PB2285: DIVERSITY OF IGG4-RELATED DISEASE: A CASE SERIES OF FOUR PATIENTS
Authors: Hind Hanani, Hajar Khibri, Yasmina Chhih, Fatima Zahra El Fekak, Yousra Moussadik, Wafa Ammouri, Mouna Maamar, Hicham Harmouche, Zoubida Tazi Mezalek, Mohamed Adnaoui
Journal: HemaSphere (2023)

Topic: 18. Indolent and mantle-cell non-Hodgkin lymphoma - Clinical Background: IgG4-related disease (IgG4-RD) is a fibro-inflammatory disease resulting in a pseudotumor syndrome affecting one or more organs. Polyadenopathies and pancreatic, biliary, lacrimal, retroperitoneal and renal involvement are the most suggestive manifestations. Diagnosis relies on proof of a lymphoplasmacytic infiltrate secreting IgG4 with or without elevated plasma levels, as well as phlebitis obliterans and storiform fibrosis leading to affected organs’ dysfunction. The diversity of presentations complicates the diagnosis. We describe here the cases listed within our training. Aims: Illustrate the diversity of IgG4-RD’s clinical presentation and diagnostic pathway’s complexity Methods: Monocentric retrospective study including four IgG4-RD patients admitted and diagnosed with IgG4-RD in the Internal medicine dept. from January 2019 to December 2022. Results: We enrolled 4 patients with a mean age of 45 years [17-67 years] and a M:F sex ratio of 1. The mean diagnostic delay was 10 months. Clinical signs consisted of an orbitopalpebral pseudotumor (50%), polyadenopathy (50%), pancreatitis (25%), Miculicz syndrome (25%) and a pseudotumor of bilateral mammary (25%), cerebral (25%) and nasosinusal (25%) localisation. Serum protein electrophoresis showed a betagamma block (50%) and a polyclonal increase in gammaglobulins (50%); mean serum IgG4 level of 7.4 g/L [1.59-20 g/L]. One patient had an eosinophilia at 700 cells/mm³. Hepatic and renal functions were preserved except in one patient with biological cholestasis. All patients benefited from a CT scan (100%), two from a PET scan (50%) and one from an MRI (25%). The lesions found were as follow: lymphadenopathy (50%), parotid swelling (50%), orbital (50%), cerebromeningeal (25%), lacrimal gland (25%), nasosinusal (25%), mammary (25%), pancreatic (25%) hypertrophy and bile duct dilatation (25%). Of the eleven biopsied sites, five (45%) found a lymphoplasmacytic infiltrate expressing IgG4, three (27%) showed non-specific inflammation, three (27%) were normal and all ruled out a specific impairment suggesting a differential diagnosis. Three of four patients exceeded the threshold of 20 points necessary to diagnosis according to the ACR/EULAR 2019 criteria. All patients were put under corticotherapy (mean duration of 16 months) and were subsequently declared on complete remission. During follow-up, two patients relapsed on an identical site (palpebral), the third one on a different site and were put under rituximab with a favorable outcome. No death was recorded. Summary/Conclusion: Despite clinical diversity, certain patterns can be distinguished and direct the clinician towards IgG4-RD, though requiring multiple investigations, justifying a significant diagnostic delay. The new ACR/EULAR 2019 classification does not require histological proof, but non-response to corticosteroids remains an exclusion criterion. Keywords: Lymphoproliferative disorder